Physics 11 Honours Lesson 3 Distance and Displacement

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1 Name: Block: Physics 11 Honours Lesson 3 Distance and Displacement In physics, every measured quantity is either a or a. Scalars: For example: Vectors: For example: Note: Vectors are either written in bold font (ie v, F), but this is hard to handwrite. So, the other notation is to put an arrow above the vector (ie v,f ), although since we are lazy we often just write half the arrow. Distance vs Displacement Distance: Symbol: Displacement: Symbol: Ex 1): Use the diagram to determine the resulting displacement and the distance traveled by the skier during these three minutes Distance traveled = Displacement =

2 Ex.2) What is the coach's resulting displacement and distance of travel? The coach covers a distance of and has a displacement of Speed vs Velocity Speed is a Velocity is a Average speed = Average velocity = Ex. 3) While on vacation, Mr. M traveled a total distance of 440 miles. His trip took 8 hours. What was his average speed? Ex. 4) Use the diagram to determine the average speed and the average velocity of the skier during these three minutes. Refer to Ex.2) What is the coach's average speed and average velocity?

3 Ex. 4) Jason is giving Peter a football play to run. a) What distance will Peter run in order to complete this play? b) What will Peter s displacement be? In conclusion, speed and velocity are kinematic quantities that have distinctly different definitions. Speed, being a, is the rate at which an object covers. The average speed is the (a scalar quantity) per time ratio. Speed is ignorant of direction. On the other hand, velocity is a ; it is direction-aware. Velocity is the rate at which the position changes. The average velocity is the or position change (a vector quantity) per time ratio. Ex. 5) In the Funny Car competition at the Joliet Speedway in Joliet, Illinois in October of 2004, John Force complete the ¼-mile dragster race in a record time of seconds. Determine the average speed of the dragster in mi/hr and m/s. GIVEN: (1.000 mi =1609 m) Ex. 6) Ken Runfast is the star of the cross-country team. During a recent morning run, Ken averaged a speed of 5.8 m/s for 12.9 minutes. Ken then averaged a speed of 6.10 m/s for 7.1 minutes. Determine the total distance which Ken ran during his 20 minute jog.

4 Ex. 7) the position-time graph below represents the motion of South's basketball coach during the last sixteen seconds of overtime during this past weekend's game. Use the graph to answer the next several questions. a. Determine the total distance walked by the coach during these 16 seconds. b. Determine the resulting displacement of the coach during these 16 seconds. c. Determine the displacement of the coach after 12.0 seconds. d. At what time did the coach have the greatest displacement from his starting position? e. What was the fastest speed which the coach walked during any of the time intervals for the last 16.0 seconds? f. What was the average speed of the coach for these 16.0 seconds? Ex. 8) Mr. M is preparing to show the class a Strobe demonstration when he realizes that his absentmindedness has struck once more. He left the strobe on the counter in the back of the lab after the last class period. Starting 1.0 meter from the front of the room, Mr. M walks quickly to the back of the lab, picks up the strobe and returns to the middle of the classroom. The position-time graph below represents his motion. Use the graph to answer the next several questions. a. What is the total distance walked by Mr. M during these 8.0 seconds? b. What is the average speed of Mr. M during these 8.0 seconds? c. What is the average velocity of Mr. M during these 8.0 seconds? d. How fast did Mr. M walk during the first 5.0 seconds? e. How fast did Mr. M walk during the last 3.0 seconds?

5 Physics 11 Honours Name Block: The passing car dilemma Driving in B.C. is a more dangerous and frustrating experience because many drivers do not realize that the slow first car is never the problem. It is the second and third cars following too close to the first slow one that develops the B.C. phenomenon known as convoys. (If you do not intend to pass a slow vehicle you should hold back to allow step-by-step passing instead of the more dangerous convoy passing described in the following problem). 1. A car wishes to overtake four vehicles moving along as a convoy. The convoy is made up of three cars (4 m each) and a van + trailer (10 m). Each vehicle is separated by 12 m, for a total of 58 m. The passing car starts to overtake 15 m behind the last car and finishes passing 15 m in front of the first car in the convoy. The time interval to pass the entire convoy is 20 s. If the convoy is traveling at 23 m/s (82.8 km/hr) what must be: a) the average speed of the passing car b) the time interval for the passing car to be alongside the convoy. c) the distance the convoy travels while being passed. d) the distance the passing car travels while passing. Suppose at 14 seconds into the pass the passing car has to break and retreat. Suppose the passing car drops instantly to 12 m/s then maintains the new speed. How long will it take the car to pull in behind the last car in the convoy, and how far down the road will the passing car travel at this new speed before it can find safety behind the last car in the convoy? HINT: Plot a graph of Displacement vs. Time with the rear of the convoy with a y intercept of 15 m and a slope of 23 m/s. Then plot the front of the convoy and the slope for the passing car. After plotting these straight line graphs write out their equations and see how you could use them to solve the problems

6 Distance vs. Displacement & Speed vs. Velocity Below is a map of a happy country that lies deep within the subconscious of crazy physicists. When they feel stressed out or sad they go to this country and ponder kinematics problems as they travel from one happy town to the next! It makes them happy! It will make you happy too! Road Distances: Fizelstein - Quaztoff = 75 km Fizelstein - Zorkbaum = 28 km Glerknoid - Quaztoff = 44 km Glerknoid - Schtropfberg = 68 km Glerknoid - Zorkbaum = 83 km Quaztoff - Schtropfberg = 27 km Rassississa - Schtropfberg = 104 km ***You will need a ruler with centimeters on it for this exercise! For each of the following, find: distance traveled (in km) magnitude of the displacement (in km) average speed (in km/h) magnitude of the average velocity (in km/h) Clearly show your work and all calculations on a separate piece of paper. *** Give your answers to the correct number of sig figs (assume all ruler measurements are accurate to the nearest mm). *** 1. From Fizelstein to Rassississa through Quaztoff and Schtropfberg in 3.5 hours. 2. Schtropfberg to Quaztoff to Glerknoid to Zorkbaum in 4.8 hours. 3. Rassississa to Schtropfberg back to Rassississa in 2.0 hours. 4. Glerknoid to Fizelstein via Zorkbaum in 7.0 hours. 5. Rassississa to Schtropfberg to Quaztoff to Fizelstein to Zorkbaum to Glerknoid and back to Quaztoff in 23.4 hours.